Yarn relaxing apparatus



1964 c. R. POUND 3,161,913

YARN RELAXING APPARATUS Filed April 19, 1962 2 Sheets-Sheet 1 Dec File

C- R. POUND YARN RELAXING APPARATUS d April 19, 1962 2 Sheets-Sheet 26a7 as \jiga E20- 8 g 5- E to- 1 l I 1 1 A00 .75 .50 .35 0

69)? kavnzzvxxva a was/1v larva United States Patent Ofiiice 3,1513%Patented Dec. 22, 1964 3,161,913 YARN RELAXENG APPARATUS Claude RussellPound, Aiken, S.., assignor to E. I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware Filed Apr. 19, 1952, Ser.No. 188,675 Claims. (Cl. 18--8) This invention relates generally to theproduction of nylon filamentary yarn and, more particularly, to anapparatus wherein such yarn structures are drawn to increased length andorientation.

Some of the problems experienced with drawn nylon yarn as a result ofits tendency to undergo a gradual lengthwise retraction on standing havebeen disclosed by Pitzl in US. Patent No. 2,956,330. For example, it hasbeen noted that the differential extent to which filaments are permittedto retract in various locations on a drawtwister package leads tovariations in such properties as denier, modulus, break elongation,dyeability and boilolI shrinkage. Such fabrics defects as pirn taperbarre have been traced to these property variations; the streakiness maybe due either to differences in dye depth, denier variations orirregularities in fabric construction related to variable shrinkage inthe warp yarn. Additionally, the compressive forces developed by thegradual retraction of packaged yarn has necessitated the use of highstrength package cores. Although the successive drawing, setting andrelaxing steps disclosed by Pitzl have proved effective as solutions tothese and other problems, they also require the application of heatunder closely controlled conditions.

The most important objective of the present invention is to provide forthe eifective relaxation of freshly drawn nylon filamentary yarn in arapid and continuous manner.

Another important object is the provision of apparatus improvementswhich facilitate the preparation of drawn relaxed nylon filamentary yarnhaving uniform properties, including a substantially undiminishedinitial modulus, through their length.

These and other objectives are accomplished without the use of heating,swellin or plasticizing agents by routing freshly drawn yarn to theinner surface of a rotating tube on which surface it is deposited bycentrifugal force and stored under substantially zero tension. Aftersufficient time in the tube to permit relaxation, the deposited yarn iswithdrawn continuously, i.e., it is withdrawn at a speed less than thatat which it was routed to the tube. This speed differential andresidence time in the tube are so related that the extent of relaxationis substantially the same for'successive yarn lengths. After withdrawal,the relaxed yarn is either Wound on a package or forwarded to a coupledprocess stage.

It the following specification, reference is made to the accompanyingdrawings wherein:

FIGURE 1 is a schematic representation of a drawtwister installationuseful in the practice of the present invention;

FIG. 2 is a sectional view of the relaxing apparatus shown schematicallyin FIG. 1; and

FIG. 3 is a comparative illustration of retract-ion values for relaxedand unrelaxed yarns.

In the yarn-drawing installation illustrated schematically in FIG. 1,undrawn nylon yarn is withdrawn from package 12, passes through thepigtail guide 14 and is wrapped in multiple wraps about driven feed roll16 and its associated separator roll 18. Alternatively, as spun yarn canbe supplied to guide 14 directly from a spinning machine rather thanfrom package 12. From feed roll 16, the undrawn yarn 10 makes one ormore wraps about snubbing pin 20 (Babcock, US. 2,289,232), and is drawnin frictional contact with that pin under the urging of draw roll 22with its associated separator roll 24. Draw roll 22, of course, has ahigher peripheral speed than feed roll 16 whence the yarn is elongatedto several times its original length. From separator roll 24, the drawnyarn passes through a rotatably driven relaxing apparatus 26 and guide28 to a smaller diameter 29 of stepped draw roll 22. Associated with thestepped-down portion 29 of draw roll 22 is a separator roll 30. Fromthere, the relaxed yarn passes through a pigtail guide 32 and is woundonto a tapered twister package 34 by means of a ring 36 and a traveler38. The tension in the yarn being wound on package 34 is controlled bythe weight of the traveler 38.

As best shown in FIG. 2, apparatus 26 includes a stationary tubularmember 40 having a yarn inlet guide portion 42 and a yarn-traversingbell portion 44 as its outlet. Bcll portion 44 terminates in a liphaving an angularly disposed peripheral edge 45. Tube relaxer 26 alsoincludes an outer tubular member 46 which is rotatably, coaxiallymounted on guide portion 42 by hearing 4%, in surrounding relationshipto stationary bell portion 44.

The illustrated embodiment is placed in use by routing freshly drawnyarn through guide portion 42 to the inner surface of rotating tubularmember 46, stringing-up the apparatus as far as guide 28, holding ortying the free end at guide 28 while permitting a cake 47 of the desiredsize to accumulate, and then stringing-up rolls 29, 3%, guide 32,traveler 38, etc. The centrifugal forces acting on the yarn as it isdeposited on cake 47 are sufficient to advance it continuously from roll24 through the guide portion 42 of stationary member 46. In excitingmember 40, it travels around the peripheral edge 45 of hell portion 44.This angular disposed edge 45 imparts a helix angle to the yarn as it isdeposited on cake 47. As a consequence, there is a surplus length ofyarn per convolution which facilitates relaxation without yarn entangle-11161111. Similarly, the centrifugal forces acting on cake 47 aresufficient to prevent twisting and turning of the cake as relaxed yarnis withdrawn from its outer layer through the open end of tubular member46 by stepped roll 29. The extent to which the substantially zerotension yarn in cake 47 is permitted to relax depends on its residencetime in that state, i.e., on the amount of yarn in the cake. Maintenanceof that amount, as the process continues, is insured by use of awithdrawal portion 29 stepped down by the same percentage that the drawnyarn is relaxed.

In actual practice, IS-denier nylon filaments have been drawn at a ratioof 4.6, relaxed in an apparatus of the type shown in FIG. 1 and comparedwith filaments drawn at the same ratio but not relaxed. The roll surface29 over which the relaxed filaments were withdrawn had an 8% step-downfrom the roll surface 22 over which they were fed to the tube relaxer.The relaxed yarn had an initial modulus of 31.91 grams/denier and a24-hour retraction of 0.49% as compared to an initial modulus of 34.7grams/ denier and a 24-hour retraction of 1.35% for the control yarn. Inaddition, 24-hour retractions were determined at a number of pointsthroughout the packages on which the two yarns were wound and the valueswere plotted, giving the curves 48, 50 (FIG. 3) for the control andrelaxed yarns, respectively. The uniform low retraction of the tuberelaxed yarns is apparent from a comparison of the curves.

Retraction values were determined from yarn samples obtained bystripping representative -150 cm. lengths from successive locationsthroughout the packages. In making such determinations, sample lengthwas determined immediately after removal from the package and before theyarn had been conditioned after drawing.

The ends of the yarn segment were knotted together, a Weight of about0.1 g.p.d. was hung on the loop, and the length of this loop measured.Loop length of such loaded samples was also measured after exposure for24 hours at 75 C., 72% relative humidity. Percent retraction wascalculated from the two sets of measurements.

As reported herein, initial modulus is defined as the ratio of change instress to strain in the first reasonably linear portion of astress-strain curve. The units employed make the initial modulusnumerically equivalent to 100 times the force in grams/ denier requiredto stretch a sample the first 1%.

Initial modulus is a useful measure of yarn resistance to lengthwisedeformation and is highly indicative of yarn behavior during subsequentpackaging, on the package and in subsequent textile operations such astwisting, quilling, Weaving, and knitting. Yarn having a high initialmodulus is relatively insensitive to tension variations encounteredduring these operations; conversely, yarn with lower values of initialmodulus is noticeably sensitive to such tension variations and formspoorer quality fabrics exhibiting the above mentioned streaks and barr.as also noted above, yarn relaxed in accordance with the presentinvention has a high retained initial modulus.

The process of this invention is useful in the preparation ofspindle-wound packages having a variety of contours, such as bottlebobbins, filling wind bobbins or headed spools and in draw-windingoperations where square or tapered shoulder packages of zero twist yarnare wound upon cylindrical cores, using conventional reciprocatingtraverse means during winding. By employing the present process andapparatus in these operations, it is possible to wind freshly-drawn yarnonto inexpensive disposable paper cores, hitherto impossible because ofthe compressive forces developed in packages of unrelaxed yarn. Byproviding a one-Way shipping package in a single operation, largesavings are realized, since repackaging prior to shipping becomesunnecessary and the need for extreme strength cores is obviated.

, The process of this invention is especially useful with yarn composedof synthetic linearpolyamides, such as those disclosed by Carothers inUS. Patents Nos.

2,071,250 and 2,071,253. The preparation and spinning of these compoundshas been disclosed in US. Patents Nos. 2,130,948, 2,163,636 and2,477,156. Examples of such polyamides are those prepared from suitablediamines and dibasic acids, e.g., from hexamethylene diamine and thepassage of yarn therethrough; a second rotatable tubular member mountedcoaxially with and in surrounding relationship to said first memberadjacent its outlet end: drive means connected to said second member forimparting rotation thereto, said second member being of unitaryconstruction, having a substantially uninterrupted inner surface adaptedto receive and carry any accumulation of yarn and being open at one endto permit the withdrawal of yarn therefrom; and means associated withsaid second member for withdrawing yarn from said accumulation.

2. The apparatus of claim 1 wherein said outlet end has a peripheraledge in a plane disposed at an angle to the axis of said first tubularmember.

3. The apparatus of claim 1 wherein said first tubular member isbell-shaped at said outlet end and terminates in a lip having itsperipheral edge in a plane disposed at an angle of :less than 90 withrespect to the rotational axis of said second tubular member.

4. In combination with a yarn-drawing installation, an apparatus forrelaxing drawn yarn, said apparatus comprising: a rotatably driventubular member having openings at each end thereof; guide means forrouting yarn from said installation, through one of said openings, tothe interior of said member, the latter being of unitary constructionand having a substantially uninterrupted inner surface adapted toreceive and carry an accumulation of yarn and means for withdrawing yarnfrom said accumulation through the other of said openings.

- 5. An apparatus for relaxing drawn filamentary yarn, said apparatuscomprising: a tubular member mounted for rotation about its tubularaxis, said member having a substantially cylindrical'and uninterruptedinner surface;

drive means connected to said member for imparting within and coaxiallyof said tubular member, said element having a terminal peripheral edgein a plane disposed at an angle of less than 90 with respect to saidtubular axis whereby to traverse yarn back and forth as it accumulatesin layers on said surface; and roll means for withdrawing yarn from theoutermost layer and advancing it for adipic acids; also comprehended arepolyamide's prepared from terminal-amino carboxylic acids, and theiramide-forming derivatives, e.g., polycaproarnide from caprolactam. Yarncounts may range from monofilaments to yarn having a large number offilaments.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. An apparatus for relaxing yarn, said apparatus comprising: .a firststationary tubular member adapted for packaging.

References Cited in the file of this patent UNITED STATES PATENTS1,990,617 Sanders et al. Feb. 12, 1935 2,153,823 Byron Apr. 11, 19392,304,212 Sowter et a1 Dec. 8, 1942 2,611,923 Hume Sept. 30, 19522,786,637 Russell et al Mar. 26, 1957 V FOREIGN PATENTS 570,986 BelgiumSept. 30, 1958

1. AN APPARATUS FOR RELAXING YARN, SAID APPARATUS COMPRISING: A FIRSTSTATIONARY TUBULAR MEMBER ADAPTED FOR THE PASSAGE OF YARN THERETHROUGH;A SECOND ROTATABLE TUBULAR MEMBER MOUNTED COAXIALLY WITH AND INSURROUNDING RELATIONSHIP TO SAID FIRST MEMBER ADJACENT ITS OUTLET END:DRIVE MEANS CONNECTED TO SAID SECOND MEMBER FOR IMPARTING ROTATIONTHERETO, SAID SECOND MEMBER BEING OF UNITARY CONSTRUCTION, HAVING ASUBSTANTIALLY UNINTERRUPTED